A murder is committed in the building where Aurélia Maudru, inspector of the judicial police in charge of the investigation, lives.

Lucien Dolo, a diamond dealer candidate for the Municipal Council of Antwerp, is the subject of a press campaign insinuating that he would be responsible for the mysterious disappearance of his brother Frédéric-Sébastien, known as Freddy during an expedition to the Congo, in which Lucien had participated. Freddy's bad reputation and the hatred existing between the two brothers gives substance to this suspicion. In order to lift the charges against her husband, Isabelle asks Inspector Wens to investigate.

A restaurant owner in the Les Halles district had her handbag stolen, containing her identity papers. Ten years later, wanting to marry her bartender, she learns that the thief who stole her bag has married a young baron, using her own name. She then decides to go to the mansion of her "legal husband" to reveal the truth and demand a divorce, causing disruption in the lives of the baron and his aunt, a countess who is very strict about traditions. Finally, it is a cardinal, visiting the castle, who finds a way out of this situation.